520h random shutdown

[MyOtherCarisaWheel Horse 10]

I have a 1995 520h bought last summer that has a random shutdown issue. When it does this if I get to the key and turn it off, then back on again, it will continue to run just fine. I replaced the ignition switch and that made no difference. I’m thinking the kill relay may be the culprit. I was next going to Hotwire the coil with a wire and alligator clip to the battery just as a test to see if it still does this. Where else should I be looking for an issue? It does this 4 or 5 times in a 45 minute window and runs fine otherwise. I also have a 90 or 92 520 for possible part swapping diagnostics.

Edited April 16 by MyOtherCarisaWheel Horse

[953 nut 51,881]

Sounds like a loose wire to me.   I would start at the 9 pin connector, You may have a wire that is corroded or very loose that isn't making continuous connection. 

[JoeM 7,674]

1 hour ago, MyOtherCarisaWheel Horse said:

going to Hotwire the coil with a wire and alligator clip to the battery just as a test to see if it still does this

Yes, will point you in the right direction. 

I seen one were the ignition module was going bad when it warmed up and would turn off intermittently. But If i was betting, my money would be on what Richard said about the 9 pin. 

[kpinnc 10,822]

And/ or the coil. 

 

The Onan ignition coil sometimes will fail intermittently when they heat up. 

[lynnmor 6,802]

You are getting some good advice.  Download the Demystification Guide and look at page 7-99.

 

[Red-Bovine 289]

Our 1992 did that and we wound up replacing the trigger under the flywheel.

[MyOtherCarisaWheel Horse 10]

43 minutes ago, lynnmor said:

You are getting some good advice.  Download the Demystification Guide and look at page 7-99.

 

Thank you, I downloaded the guide and I think I’m on the right track. If I jump juice directly from the battery to the coil and the issue is fixed I can assume the trigger module is ok I believe. I think the seat safety switch is already jumped as it runs with no one on the seat. My older 520 had issues with the molex plug and fuse block. I cut that all out and put an aftermarket plug and fuse bus in it and had no further issues in the 10 or 12 years since. Since I got the 95 the older one is relegated to driveway plowing and grading duties so it doesn’t see the usage it used to.

[JoeM 7,674]

7 hours ago, MyOtherCarisaWheel Horse said:

If I jump juice directly from the battery to the coil and the issue is fixed I can assume the trigger module is ok I believe

yes

[Handy Don 10,656]

10 hours ago, MyOtherCarisaWheel Horse said:

I believe. I think the seat safety switch is already jumped as it runs with no one on the seat.

If this “hot wire” is faulty, the engine will die. 

I’d encourage you to restore the seat switch, in any case.

(For emphasis, read the “Rookie Mistakes” thread)

Edited April 17 by Handy Don